textproduct: Quad Cities

KEY MESSAGES

- A prolonged period of wet weather will be seen through late week, as rounds of rainfall pass through the area, some heavy at times.

- A Flood Watch has been issued for areas expecting to see the heaviest rainfall, which will lead to rises on area rivers and potential areal flooding.

- A drier and cooler weather pattern will set up this weekend and into early next week.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 152 AM CDT Wed Sep 30 2026

We are in for an active stretch of weather through Thursday night, as a system digging into the southern Rockies tracks towards the Upper Midwest. Ahead of this, we will see a baroclinic zone set up over the region, with persistent bouts of vorticity moving overhead. This pattern is also favorable for anomalous amounts of moisture pumping into the region, owing to the tropical connection of the upper level jet stretching from the Eastern Pacific and the LLJ bringing moisture into the area from the Gulf. Thus, we will have plenty of moisture and forcing moving overhead through the next 48 hours. For our area, this means that we are in for a prolonged stretch of wet weather. Our forecast area falls under the area where we will generally see continuous forcing, resulting in persistent rainfall, where heavy rainfall can be expected. While there will be some dry time between showers, we are expecting to remain damp and showery throughout much of this timeframe. There will be a few rounds where the heaviest precipitation is expected to fall. The timing of these rounds will generally be through the day today, tonight into Thursday AM, and then again Thursday night into Friday AM. These more intense rounds of precipitation can be attributed to increases in the LLJ as stronger vort maxes approach. Again, we will continue to see rainfall chances between these, but these will be the best time frame for heaviest rainfall. PWATs will be unseasonably high, roughly sitting around 2.00"+, favoring heavy/efficient rainfall. There will be the chance for embedded thunderstorms as well, which could locally enhance rainfall rates, but should remain largely isolated owing to weak instability and shear.

Looking into total rainfall accumulation when this ends Friday AM, guidance is honing in on a sizable swath of 2-3" of rainfall for much of our forecast area. Given the environmental setup, there will be some locations exceeding 3", but confidence on the location and coverage of these higher-end amounts is low. Guidance continues to fluctuate north and south with the axis of heaviest rainfall, with the latest 00z runs having a northward shift in heaviest amounts in the REFS/NAM guidance. Thus, there remains some uncertainty on where the heaviest axis will setup. Although, much of guidance generally keeps this axis between the Interstate 80 and Highway 20 corridors.

Areas that see the heaviest rainfall will have a low-end flash flood threat, with WPC highlighting our area in a Slight Risk, level 2 of 4, for Excessive Rainfall. One thing that might limit the flash flood threat will be the duration of rainfall. We are not expecting this rainfall to fall over a three hour period. Rather, we expect these totals over a 24-48 hour period. Thus, the long duration should allow for more infiltration than a short duration heavy rainfall event. Rises along area rivers can be expected, especially areas that saw rises with the recent heavy rainfall, with some areal flooding also possible. Thus, we have opted to issue a Flood Watch roughly along the Highway 30 and Interstate 80 corridors, as well as areas farther southwest towards Fairfield, Iowa.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 201 PM CDT Tue Sep 29 2026

Friday through Tuesday Assessment...medium to high confidence (50-70%) of dry and cool conditions

By late Thursday night and into Friday morning, rain will end from northwest to southeast. Friday afternoon looks to be cool with temperatures only in the 60s.

Starting this weekend and continuing into the first half of next week cool fall-like temperatures are expected. The global models have been advertising this scenario for over a week but have slowly shifted the brunt of the coolest air to the eastern Great Lakes and New England.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1232 PM CDT Wed Sep 30 2026

Poor flying conditions are expected through much of the TAF period at CID/DBQ, with low IFR/LIFR conditions. Opted to go more pessimistic at these terminals given the very moist BL and low level atmospheric profile shown on our 18z DVN sounding. A brief improvement to VFR is likely at MLI/BRL this afternoon/early evening before dropping back to MVFR overnight. Another round of showers and possible embedded storms will move across western and central IA this evening arriving into eastern IA after midnight. Decided to leave thunder mention out of the CID TAF for now since progged lapse rates and instability will be marginal at best. Brief periods of moderate to heavy rain is possible at CID/DBQ early Thursday, with vsbys under 2SM and cigs under 1kft.

HYDROLOGY

Issued at 1232 PM CDT Wed Sep 30 2026

Many of the area rivers have not fully returned to normal streamflows after the last rainfall event in mid-September. That leaves them primed for additional flooding where the higher rainfall totals end up over the next couple days, especially along the Iowa and Skunk rivers. Several river watches and warnings have been issued where flooding is most likely to occur. There will also likely be rises along the Mississippi River especially south of New Boston. These river forecasts are largely based on rain that hasn't fallen yet, so the forecasts will likely be adjusted once we see how much rain falls and where the highest amounts are across the area leading to a higher confidence in flood category. Please keep an eye on forecast and updates to flood products in the coming days.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Flood Watch through late Thursday night for IAZ040>042-051>054- 063>068-076>078-087>089-098. IL...Flood Watch through late Thursday night for ILZ007-009-015-016- 024. MO...None.